Diethylpropion hydrochloride, 1-phenyl-2-diethylamino-1-propanone hydrochloride is a known sympathomimetric agent which is highly useful for its anorexigenic properties. This compound and its properties are fully described in U.S. Pat. No. 3,001,910, and has been marketed for a number of years in tablet form as Tenuate.RTM., diethylpropion hydrochloride USP (Merrell Dow Pharmaceuticals Inc.), and also as a sustained release tablet, Tenuate Dospan.RTM., diethylpropion hydrochloride USP for the treatment of obesity.
It would be highly desirable to provide a diethylpropion hydrochloride formulation that would be suitable for use with either hard or soft shell gelatin capsules. Not only is there a preference in some patients for a drug to be administered in capsule form, but capsule formulations generally permit the drug to be administered in a more concentrated form having fewer excipients added thereto. Furthermore, capsule formulations are tasteless, easily administered and generally provide greater stability as compared with tablet formulations inasmuch as such formulations remain free from those variables introduced during the compression of tablets. Moreover, capsule formulations are generally free from various additives such as stearates, binders, dispersing agents, coatings and flavoring agents that are generally required in tablet formulations.
The search for an alternative dosage unit form for diethylpropion hydrochloride, more particularly a sustained release capsule dosage unit form has not been without difficulty. Quite unexpectedly, the uncompressed tablet granulation, when placed in either a hard or soft shelled gelatin capsule, did not produce the desired sustained release effect. After many unsuccessful attempts, I have discovered a stable formulation of diethylpropion hydrochloride which is suitable for administration via either hard or soft shelled gelatin capsules, which is stable, and which will provide the critical timed release pattern that has been approved by the Food and Drug Administration.